A242538 Squares that are sum of digits of factorials.

1, 9, 36, 81, 144, 225, 324, 441, 729, 1089, 1296, 2025, 2304, 2601, 2916, 3249, 3600, 3969, 4356, 4761, 6561, 7056, 7569, 8100, 8649, 9216, 9801, 10404, 11025, 11664, 12996, 13689, 15129, 16641, 17424, 20736, 22500, 23409, 26244, 29241

Offset

1,2

Comments

Intersection of A000290 and A004152.

Links

Table of n, a(n) for n=1..40.

Example

a(5)=144 for 33!=8683317618811886495518194401280000000 whose sum of digits is 144=12^2. a(5) is also originated from 34! and 35!.

Mathematica

Union[Select[Total[IntegerDigits[#]]&/@(Range[2500]!), IntegerQ[Sqrt[#]]&]] (* Harvey P. Dale, Feb 20 2015 *)

Prog

(PARI) lista(nn) = {v = vector(nn, n, sumdigits(n!)); Set(select(x->issquare(x), v)); } \\ Michel Marcus, May 18 2014

Crossrefs

Cf. A066235.

Sequence in context: A297584 A073946 A016766 * A083353 A083014 A202287

Adjacent sequences: A242535 A242536 A242537 * A242539 A242540 A242541

Keyword

nonn,base

Author

Carmine Suriano, May 17 2014

Status

approved